Gas burner



Aug. 14, 1962 D. LABlNO 3,049,172

GAS BURNER Filed 001;. 22, 1955 FIG-l INVENTOR.

DOMINICK LABINO BY fizdwwmw ATTORNEYS United States Patent 3,049,172 GASBURNER Dominick Labino, Toledo, Ohio, assignor, by mesne assignments, toJohns-Manville Fiber Glass Inc, Cleveland, Oh o, a corporation ofDelaware Filed Oct. 22, 1953, Ser. No. 387,770 3 Claims. (Cl. 15899)This invention relates to burner apparatus in which combustible gasesare burned within a chamber and the gases of combustion are caused to bepassed therefrom at high velocity and high temperature through a narrowslot or mouth. More particularly the invention relates to thearrangement of the slot or mouth of such a burner.

The burners generally referred to above find particular utility infibrous glass production; to produce fine fibers molten glass may beformed into streams and the streams may be attenuated into filamentaryform as the glass cools; these filaments when subjected to a hot gaseousblast of a burner may be then blown into very fine diameter staplefibers. Fibers having diameters of less than one micron have beenproduced in this manner.

To produce such fibers in uniform diameters it is essential not onlythat the primary filament diameter be closely controlled but that theblast itself as to velocity and temperature be maintained within narrowlimits.

The burners customarily employed have a relatively large chamber inwhich the gases are burned and the expanding gases issue through arelatively narrow slot defined by lips in the wall of the chamber,thereby attaining a high gaseous velocity at an intense heat.

The portions of the burner, including the lips, which are contacted bythe hot gases of combustion are of a refractory material, usuallyCorundum, which is approximately 96% aluminum oxide. The long narrowslots formed in this refractory in the cold have heretofore beenrectangular in shape as formed.

It has now been found that under the influence of the heat whichgenerally is above 3000 F. that the rectangular lips, even of a highlyrefractory material such as Corundum, tend to close centrally early inservice life. This tendency is accentuated by the impracticability ofsupplying a support centrally to the upper lips and also by the tendencyfor the refractory to shrink under service conditions.

That the central closure in whole or part of the lips is highlyimportant in the production of uniform fibers is clearfor the velocityof the gases will vary materially over the length of the lips,increasing as the spacing therebetwen decreases, occasioning a varyvelocityas well as varying heat effects-on the filaments to be blown tothe fiber form; this results in non-uniformity thereof.

A complete closing of the lips about the central portion of the lengthof the slot has been found to exist in some burners upon their removalfrom service. Such condition does not permit the attainment of thesubstantially planar gaseous blast which is required for optimumproduction of thin blown material. I

The height of the slots employable is so slight that detection ofclosure or partial closure under operating conditions is diificult dueto the several factors which influence burner operation. It has now beendetermined experimentally however that closure or tendency to closecentrally upon initial heating as well as over the life of the burnermay be avoided by so constructing and arranging the refractory of theburner lips as to provide a uniform opening across the mouth of theburner under operating conditions.

It is therefore a primary object of this invention to describe animproved burner apparatus for the blowing of glass fibers in which theslot of the burner will be of uniform rectangular cross-section underthe most severe of operating conditions.

It is a particular object of the invention to describe an improvedarrangement of a burner slot which permits of long, trouble-freeoperation at maximum blast velocities and blast temperatures.

These and other allied objectives of the invention are attained byproviding the cold refractory of both the upper and lower lips of theburner with an arcuate form, the lips each being curved outwardly withrespect to the slot. This effectively provides in the cold burner awider mouth or slot at the central portion and when placed in servicethe arcuate refractory lips tend to straighten out providing arectangular operating opening capable of delivering a gas flow ofimproved uniformity of velocity across the mouth of the burner.

The specific degree of are which is required in the lips is dependentupon the particular refractory material which forms the lips; the degreeto secure materially improved results is surprisingly slight however aswill be noted from the specific example which follows hereinafter. Ingeneral the degree of curvature is principally dependent on theshrinkage of the refractory under service conditions, the servicetemperature and the lip length, and the desired width of the slotitself.

The invention will be more fully understood by reference to thefollowing detailed description and accompanying drawing wherein:

FIGURE 1 schematically illustrates apparatus useful in the practice ofinvention and which apparatus incorporates the burner having the liparrangement of invention;

FIGURE 2 is an elevational view of the burner particularly illustratingthe contour of the burner lip; and

FIGURE 3 is a view illustrating a portion of the burner appearatusincluding the lip arrangement.

Referring to the drawing the numeral 10 indicates one embodiment offiber-forming apparatus in which a supply pot 12, constructed ofplatinum for example, for retaining molten glass, is surrounded byinsulating material 13. The glass is made molten and retained in themolten state by the application of heat energy through induction heatingcoils indicated at 14 supplied from a high frequency source (not shown).

Solid glass in the form of marbles 15 is fed automatically from thehopper 16 to the pot 12 through a trap door mechanism 18 which issuitably controlled to permit feeding of the marbles in response to thelevel of the liquid in the pot 12. By this means glass is fed into thepot at the same rate at which it is withdrawn through the apertures 20in the base of the pot.

As the glass exudes from the apertures 20 and cools primary filaments 22are formed and as they solidify they are passed over guide roll 24 todrawing rolls 26; the drawing rolls 26' are spaced at a suflicientdistance below the pot 12 such that the glass will have hardened beforeit passes through the rolls themselves. The rolls preferably havesurfaces of resilient rubber which frictionally engage the glass and dueto the high speed of the rolls feffects a drawing to form finefilaments.

'Ihe filaments passing from the drawing rolls are fed over a secondguide 28 and are presented in parallel relation and alignment over theV-shaped edge 29 of the block to a hot high velocity blast of gasissuing from a burner 30; burner 30 is supplied through conduit 33 witha suitable fuel mixture for combustion within the burner in the mannerknown to the art. The heat of this issuing gas blast softens thematerial of the filaments and the velocity of the blast causes thesoftened material to be attenuated still further; the blown materialthen passes under the influence of the force of the gaseous blastthrough conduit 32 to be collected at a suitable receiver (not shown) atthe remote end of the conduit.

It is essential to uniformity of production that the hot gas blastaffect each of the primary filaments 22 uniformly and to this end theburner lips must provide for uniform passage of the gas blast.

In the practice of the invention therefor the burner 30 is provided at34 with a slot or mouth, the shape of which may be more clearly seen inFIGURE 2. The lateral sides a and b of the mouth 34 are rectilineal,whilethe upper and lower lips 36, 38, respectively, are slightlyarcuate, each being in fact convex outwardly with respect to the slot ofburner mouth.

The material within which the lips are formed is usually a suitablerefractory such as corundum; whatever the specific material the upperlip 36 is subject to three distinct distortion effects when the burneris placed in operation; that is shrinkage of the refractory materialitself, which tends to compact the material, a tendency to expand underheat, which is greatest at the lip surface and consequently results inunequal stresses in the body of material, and the tendency of thesubstantially unsupported upper lip to bow centrally. The formation ofthe upper lip in arcuate form turns these effects to advantage for thearcuate lip straightens out to assume in operation the contour shown bydotted line 39 in FIG- URE 2. Similarly the lower lip 38 which islikewise subject to the shrinkage and heat is shortened by these effectsand it assumes the straight line or rectilineal form indicated at 40.

The sides a, b are maintained rectilineal to give to the structure asmuch support as is possible and to maintain a sharp area of blast gases.

In specific application it has been found that a slot, formedrectangular in the cold 'recractory, and having a dimension of A for thesides a, b and a width of about 4" will over a period of service distortand 'close completely. By forming the upper and lower lips in smoothcurve extending between the rectilineal sides it, b, which have the samedimensionthe central spacing between the lips need only be to materiallyimprove the burner service conditions and burner life.

Thus the lip arrangement of invention under service conditions providesan issuing blast of gases in rectangular shape which gases contact thefilaments passing over "the V-shaped edge 29 of block 28 uniformly.Further over a long period of service life the lips do not close andthis permits a material reduction in equipment shutdown time thusincreasing productivitya factor which has hitherto been of considerableeconomic importance in the production of glass fibers.

It is to be understood that while the invention and specific examplehave been set forth with reference to 'coiunduin the invention is not tobe limited to a specific refractory material for the burner lip but isto be considered as applicable to anysuitable refractory or combinanonof refractories the lips of which would be subject to the stressesdesignated hereinbefore;

'It will be understood that this invention is susceptible tofihodification in order to adopt it to different usages andconditionsan'cl accordingly, it is desired to compreh'ehd suchmodifications within this invention as ma fall within the scope of theappended claims.

I claim:

1. In a gas burner capable of emitting hot ases bf combustion in planarform for the hot gaseous blowing of thermoplastics into fine fibers, avertically extending wall formed of corundum, said wall having atransverse slot therein defined by opposed upper and lower lips, saidslot having rectilineal sides joining the opposed lips and the lips inthe cold inoperative condition of the burner being each arcuate in formand curving uniformly in a vertical plane with respect to therectilineal sides said rectilineal sides being spaced about 4 inchesapart, said lips defining a spacing about A inch larger, at theirgreatest point of separation, than the dimension of one of said sides.

2. A gas burner, capable of emitting hot products of combustion inplanar form and having wall portions which are in direct contact withsaid products of combustion, comprising a refractory wall portion havinga pair of opposed lips and a pair of opposed lateral sides transverse toand joining said lips, said lips and said sides defining an elongatedoutlet for discharging said products of combustion, said lips in thecold inoperative condition of the burner being each arcuate in form,substantially greater in length than said sides, and defining a spacingat their greatest point of separation larger than the length of one ofsaid sides, said refractory being susceptible to deformation whensubjected to elevated temperatures of a predetermined order, saidspacing between said lips and the length of each lip being ofpredetermined magnitudes interrelated with the degree of deformation ofsaid refractory so that each of said lips will assume a substantiallyrectilineal shape upon subjection to elevated temperatures of saidpredetermined order, and said lateral sides being of sufficient lengthto maintain a sharp area of blast when said burner is in operation.

3. A gas burner, cap-able of emitting hot products of combustion inplanar form and having wall portions which are in direct contact withsaid products of combustion, comprising a refractory wall portion havinga pair of opposed lips and a pair of opposed lateral sides transverse toand joining said lips, said lips and said sides defining an elongatedoutlet for discharging said products of combustion, said lips in thecold inoperative condition of the burner being each arcuate in form,substantially greater in length than said sides, and defining a spacingat their greatest point of separation larger than the length of one ofsaid sides, said refractory being susceptible to contraction whensubjected to a temperature in the order of 3000 F., said spacing betweensaid lips and the length of each lip being of predetermined magnitudesinterrelated with the degree of contraction of said refractory so thateach of said lips will assume a substantially rectilineal shape uponsubjection to said temperature, and said lateral sides being ofsufficient length to maintain a sharp area of blast when said burner isin operation.

References Cited in the file of this patent UNITED STATES PATENTS1,045,475 Van Zandt Nov. 26, 1912 2,367,119 Hess Jan. 9, 1945 2,614,619Fuller on. 21, 1 952 2,681,696 Stalego Jun-e 22, 1954 FOREIGN PATENTS1,631,448 Trance Mar. 18, 1953

